Appliance for bending tubing



' March 20, 1945. F. c. DRAPER APPLIANCE FOR BENDING TUBING Filed. Jan. 27, 1945 2 Sheets-Sheet l March 20, 1945. F. c. DRAPER 2,372,063

APPLIANCE FOR BENDING TUBING Filed Jan. 27, 1943 v 2 Sheets-Sheet 2 Patented Mar. 20, 1945 APPLIANCE FOR BENDING TUBING Frederick Cecil Draper, Chipping Sodbury, England, assignor to Parnall Aircraft Limited, The Aerodrome, Yate, near Bristol, England, a British company Application January 27, 1943, Serial No. 473,737 In Great Britain April 22, 1941 .6 Claims. (01. 153 -45) This invention relates to the bending of tubes and is particularly applicable to the formation of a number of bends in a length of tube of metal which can be bent in the cold and, for example, of metal such as annealed copper, mild steel or aluminium alloys which have been normalised.

The object of theinvention is to provide bending appliances which enable bends to beformed in tubes expeditiously by means of unskilled labour and as free as possible from deformations of the cross-sections of the tubes such as may be occasioned by kinks, flattening on the outside The inventionis in fact concerned with tools I for use in the method of bending which is well known and in which profiled forming dies are employed, the tube to be bent being clamped at one point 'to the die and bent down into contact with the profile by a lever-like tool which can exert pressure on the outer surface of the tubes. In machines which have been proposed for that purpose, a handle or shaft-to be used as the bending lever was to be pivoted to the forming die at the centre of the arc-shaped portion of the profile and a grooved slipper or block with a straight working surface, arranged in a part of the tool forming a housing for the slip,- per so as to be pressed into contact with the tube to be bent and so as to be capable of sliding in the housing, the pressure being applied by a roller on the back of theslipper at a point opposite the pivot of the handle.

The present inventionprovides a form of bending appliancein which the bending is rendered more'gradual by providing a second roller to pres upon the back of the slipper at a point in advance, in the direction of bending, of the roller which is opposite thepivot and which thus acts at the point of maximum bending moment while the housing in which the slipper is arranged to slide is itself arranged to slide relatively to the head of the appliance and to be secured to the head when the slipper has been brought into contact with the tube to be bent. Such an appli-' ance made in accordance with the invention may be readily arranged for making. both clockwise and counterclockwise bends by forming in its head two alternative apertures for engagement with the pivot on the forming die, each having its axis in a plane at right-angles to the length of the slipper and containing the axis of one of the said two rollers; then if one of the apertures is utilised, the roller opposite it bears on the slipper at the point of maximum bending moment and,'in effecting the bend, the appliance is turned about the pivot in the direction such that the other roller bears on the slipper at a point in advance of the point of maximum bending moment.

In a particular form of construction, the said housing is carried by a sleeve which is arranged to slide on but not to turn with respect to the shaft so. that the slipper may vbe brought into contact with the tube to be bent and held by moving the sleeve along the shaft andsecuring it in position. The slipper may be arranged to slidein a channel between cheeks'in the housing which is furnished with pins or projections engaging in grooves inthe sides of the slipper. In order to prevent the slipper leaving the housing and to limit the amount'of the relative displacea seating or bedding surface for the die may be provided with a'key-hole slot, to receive a bolt by means of which the forming die is secured and which also constitutes the pivot for the bending appliance; the forming die may the be prevented from rotation by providing a projection integral with it which also engages the slot in'the bracket. Thetube to be bent may be held against the forming die to prevent springback by a screw cramp which is secured to the die by a pin fixed to the latter engaging a notch Y in the side of the'body of the cramp.

' example of-a bending appliance and examples of I appropriate shapes and with .their seating surfaces set at appropriate angles in order that bends may be easily made in planes at any desired relative angles and at any desired points along the length of tubing.

In order thatflthe, invention may be clearly understood and readily carried into eifect, an

forming dies with which it may be employed will now be more fully described with reference to the accompanying drawings in which:

Figure 1 is a plan of a'bending machine acdie and bracket as seen in the direction of thee.

arrow B in Figure 1;

Figur 4 is a similar view of a; third-"form'of athe tube being bent on a previous die.

ening up a nut 8 on to the bolt 6 so as to draw the larger part E a of its shank into the enlarged end of the key-hole slot 3. In this way, the parts are prevented from sliding in the slot 3 and rotation of the forming die 4 is prevented by engagement of a pin 5 integral with the forming die 4 in'thenarrow part oi thesiot 3. The formingdies d'. can be'readily moved'out of the way when necessary to avoid obstructing the sweep of This is effected by, loosening the nut 8 sufiiciently and forming die and bracket as .seen in-=the=.direetion=. of the arrow C in Figure 1;;While.-.

Figure 5 is a similar elevation.of.a:.fourth.ems bodiment of forming die and bracket for forming bends in a plane intersecting .those of-athelbends formed by the dies shown in Figures :2.-.to 4-;

Figure 6 is a side elevation of a bending tool or appliance adapted for use in bending tubes=on theiormingfliesshown in Figuresfi to. 5, .the. appliance. being 1 shown... in.. co.-..op eration. with a forming. die. according to.. Fig ure 2'. or. Figure. .3;

Figure 7 is an elevation.-of..lthe. applianceseen. at right-rangles. to Figurefi, ,with certainpa-rts. in section;

Figure. Bissau elevation of. a.forming .die. with a cramp. in position. .for.holdir1g. .the.tube to babent. to. the forming die..at.. the entering, point of. the. latter; and. A

Figure 9. is. at plansview of..-the.device.shown. in. FigureS:

tIn Figures- 1L to.,5..of..the drawings-,.. .is the .bed=- plate- Of: the bending; machine. to. which four. bracketsla, 2b, 2c; and 1d .of.difierent-.configura-- tions are.:secured by, screws; lit... The. brackets. serve .for anchoring,inpositiomtherfour forming. dies. .4- so. as.- toeenable; four. bends -to be deemed. imsuccession in asmglelengih. oftube-25in. different-planes.

Itwill be seen.that...each ofthe. forming-dies. 4 consists of a steel plate with a profiledperiphery of:..a., shape. to ..give.-.the -desired .shape to..the bend; tlieprofile consists oiamarc-shaped' portion-.with a straight. onflat'portiontoleitherside to limit. the. amount loi overbendl. However, .theshape: of.- the.forming dieeiszusualm. notthafinah shape. .01. thetubedesired but isnmade to allowv for. a slight .-.spring. back of;fthertube when -the..

latter is. released from engagement with'rthedier 5 The periphery, of. eachionning, dieJl. is. formed. with. a. groove 9: having. a. crossesection .conforme. ing to. one. half... ofthe. outside of the .tube .to. .be bent...

Each. forming, die isbedded'omto ,a..flat. sur..-

positionbythe ioll'owingmeansi' A slot .3? ofikey:

hole form iSJPIQViddiHLBfiCh .ofithebrackets and a bolt 6 engages a hole in the forminggdiethe. axis of. whichJies at the .centrelof'the arc-shaped portionof theprofileof'the.forming diefi. The shank of.the..bolt'6;has apart-.611 which'fits the enlarged. end' of the .kew-h'ole slot .3l and'a screw threadedpartjb.oi'smaller diameter which can slide in thenarrower part oi. the keg-hole slot 3'. The forming dieATis.lockedinpositi'on by tightaging-ha keyway 221 in.the-part .i B ofjthe, housing {3, ,butlthe' sleeve can. slide. over. the. handle 20.- to.

4 shoe or'slipper M1 pushingthe-bolt G axially until the smaller part Gbofitsnshankengages in the slot 3 when the wholeicangslidealong the slot 3. Then when it isidesiredato': position the forming die 4 accurately and lockit in-position, the bolt 6 is caused to. slide along..the...slot 3 until it engages the enlargedqend; of the slot, whereupon the nut 8 is tightened to draw the larger part 6a of the bolt 'i-"lnto the slot 3. The bolt 6 is formed with aacheese. head .1. whichalso. serves ..as..a. .pivot for theibendingto'ol ior appliance. as-willbeexplained.

below.

In making arb'endjn the...tube.29., the..-part ofv the tube.wherel it. enters the..gro.o.ve. 9,.in .the forming ,die 4 .hasto .be. heldfirmlyragainst the die so as to prevent it from being sprung, away.

from the die. 3. during; the .bending,operation.

A "simple .arrangement'for. this. purpose .is shown in'liigures 8.'andj 9. A furthenpinulflprojectsfrom; thev vfate of f the .forming die, 4 .in position to engage. a, notch. l.l.in the..body of..a screw.

cramp l2f. Whenthis.cramp l21.is tightened, it. efiectively holds thet'ubezll .atjthe entering point.

in the groove Qin the forming died.

The tube 29,.thusheldjn position,. is bent into contact with theprofile of."the forming. die. 4- byumeans of the toolor appliance shownin Fig.1;

pliance to turn with respect" to the.v forming die, 4; which is lockedto the bracket ZTwinthe manner.

already described.

The appliance consists. .of .ahandleoi: shaft 20.

h'avingat its uppenend a.headj,26"provided..with

to engageover th'epivot ,l",.and..a bl'cickcompris: inaaa sleeve. l9 screwed into..a. housing. I3ffor. a

from.turning- ,on the handle ZlLby akey- 21' en.-

briiig the slipper Mtowards. or away from. the tube 29. to .be .bent andiinorderto. ho1d the.slipperv M in contact with the tube. 29;,a nutf.23 with.

b'endson forming dies of different radii..with the.

minimum of readjustment. The. slipper. I4 is a bar. with a. straight upper. working, surface but. with its. upper surface .shaped'ito'conform with.

the cross-sectionoithe tube. 29;. it...is. housed between cheeks l3a..ofthe. housin l3. to slide in the, channelbetween those cheeks. The.cheeks,

I311 are providedwith. pins I52 engaging in'chan nels'lfi in the slipper. 14. Below the slipper M a pair ofjthrustrollers H are journalled'in the housing l3.and'it willibepbservedjthat the axis.

ofeach loi'th'e rollers llilies in.a plane at rightanglesto the. slipper l4lwhich alsopflsses through the.axisofonerofthe holes 21;" 21a: Thepur- The sleeve l 9" is prevented.

pose of that-arrangement is 'as follows." When one of the holes, for example, as shown-in Figure 6, the hole 21a, engages the pivot I, one of the rollers I1- is immediatelybpposite the pivot I while'th'e other roller I! is laterally offset! In Figure 6, the bend'has just been completed by a clockwise turning of the handle about the pivot I.

hand roller I1 is in advance of that point in'the direction of bending and thrusts'on the slipper I4 to effect the'first stage in bending'thetube 29; Ha counterclockwise bend is to be made, the hole 2'! is engaged with the pivotl and the functions of the tworollers II are interchanged, the

right-hand roller I! then being in advance of the point of maximum bending moment in the direction of'bending. During the bending operation, the slipper l4-slides in the housing l3 but does Therefore, during the bending, the right-hand roller II maintains contact between the slipper l4 andthe forming die at thep'oint of maximum bending moment, while the' left a -rollerf mounted in said housing to bearup'on;

the rear face of said slipper and journaled about J an axis lying substantially -in =a plane perpen dicular to the lengthof 1 said slipper and pass ing through the axis of one of said apertures and as'econd roller also mounted in-saidhousing to bear. upon the rear face of saidslipper and -jour..=. nalle'dabout an axis lying substantially intasecr-l;

/ ondplane-perpendicular to the length "of said;

not slide relatively to the tube 29. The slipper 1 I4 is furnished with stop plates 28,- 28a at its ends to prevent the slipperleavingthe housing and to limit the displacementof the slipper l4 with respect to the rollers II and consequently with respect to the housing 13'.

The course of an operation consisting in mak ing anumber of bends in a length of tube 29 can be described with reference to Figures '1 to 5. f.

In the case of a thin-walled tube, it is first filled with a material which will prevent the tube walls from collapsing or becoming distorted in the neighbourhood of the bends. For this purpose, a powdered material may be used or a material which can be introduced in the molten condition and allowed to solidify within the tube. The tube 29 is then set by bringing a collar or union 3| clamped to it against a setting stop lb fixed by screws to the bed-plate I and the tube is next clamped at the point to be bentto the left-hand side of the first forming die 4 as seen in Figures 1 and 2. The appliance shown in Figures 6 and 7 with the nut 23 slacked back is applied to the pivot I, the hole 2! being used as a counterclockwise bend is to be made. The second forming die 4 shown in Figure 3 is moved out of the way by loosening the nut 8 and sliding the bolt '6 down the slot 3 as already described. Theslipper I4 is located below the tube 29 and broughtup into contact with it by tightening the nut 23 and the bend efiected by a counterclockwise movement of the handle 2llso that the tube 29 is given the shape seen in Figure 2, the slipper l4 ironing out the tube on the straight profile of the forming die to ensure the correct bend. The tube 29 is next clamped at the appropriate point to the second forming die 4 shown in Figure 3 after that die has been locked in'its correct position. While the first forming die 4 supports the part of the tube 29 which has been bent,,a second bend is then made in a similar way to the first except that, as itis a clockwise bend, the hole in Figure 1.

I I claim:

1. An appliancefor bending tubing to conform slipper and passing throughthe axiscof the sec- 0nd of ,said apertures.

An appliance for bending tubing to form "to the profile of a forming diecomprising a shaft with an integral head formed with a pair,

of alternative aperture for engaging apivot on J the forming die and relatively displaced perpe -I dicular to the axis of said shaft, a'housing:,'slid ably mounted on said shaft and {formed with a channel directed transversely, to. said shaft a: 'bearing'slipper mountedfto slide said channel: and to move with said housing into'con'tactwith" the tubing to bebent, a plurality of projections directed inwardly from each of the side walls of said channel to engage in longitudinal grooves in the sides of said slipper, a roller mounted in said housing to bear upon the rear face of said with an integral headformed with a pair of alternative apertures for engaging a pivot on the forming die and relatively displaced perpendicular to the axis of said shaft, a housing slidably mounted on said shaft, a bearing slipper slidably mounted in said housing to be moved with the latter into contact with the tubing to be bent, a roller mounted in said housing to bear upon the rear face of said slipper and journalled about an axis lying substantially in a, plane perpendicular to the length of said slipper and passing through the axis of one of said apertures, a second roller also mounted in said housing to bear upon the rear face of said slipper and journalled about an '4. An appliance for bending tubing comprising,

a die-supporting bracket plate formed with a key-; hole slot, a profiled plate constituting a forming die, a bolt passing through said profiled plate and engaging said key-hole slot to form a pivot l for a bending tool, said .bolt having a portion of larger diameter to fit the enlarged end of said hem-mm and. ne llexr. oiw lerrdiemeten slide.- l i said se .191s l b. a. nut n; threaded eiisfissme tlw t and.- belt to. draw, he po tinn fiteebdiame er th eo int -t e nlar d. end: S. said? er -hole? slot o l n ien; and; se ure-sai prpflled. mate; to; said supporting bracket plate isgseenred t sa-id s pp rtingbracketplate;

5.; An appliance forbending tubing compris-r ing, a dieesupporting'bracketplate formed" with a-kex-hole slot; a, profiled plate constituting a forming'die, a bolt 'passing-through said profiled plate and engaging said key-hole slot toform a pivot for-a bending-tool, a nut in threaded engagement with said bolt for clamping said proplate to said die-supporting bracket plate,- a projectipn integralwitli said profiled plate and engaging saidkey-holeslot to prevent rotaticn tsa sL-prq lledf pl e. re a i ely. to a pport: ns e dset. la e. a. pee. p ect n time. the. ssenisaislrmfiled .n at int e ne slibeur qed. Qf bden l d f tbepmfilethereoi.and. a. scremramp. fo med. tha. not h. en aged. by, bidnsg, nah1e.. he. ub .ng to 'bebent tube.

2.;33 '232l0d31 v held. againstt the profile: oi said; pmfiled. plate at:

hegenterin r end thereei.

6. appliance. fer bending: tubin commie-- ing; a die-supmmng.bracket'plate formed with;

= a, key-hole slot, a; profiled plate constituting, a.

formingrdiei abQlt passin through said pr filed: plate; and, engaging; said, key-hole slot: to, formapivot fQIt at be ding tool, Said: bolt having. a p.02.- tionyqfi larger; diameter to. fit. the enlarged end. oirqsaid; key-hole slotand a, portion of. smaller diameter: to, slide me saidkey-hole.- slolr, a. nut; in: threadeden agement; with said bolt to draw the; DQ itiQIl of larger; diameter-thereof into the en.- lar edz end of: saidkey-hole: slot, to; position and seeur said profiled plate to said supporting; braqketplate; and; on beingislackened, .to. permit; he: gortion. o f=:said bolt of' smaller diameter to slide-Am saidkeY-hole slot; aprojection' integral. wi;t1r;said;profiled; plate to engage said key-hole slot; and; prevent rotation" of: said. profiled platev when sameis secured tosaid; supporting: bracket plate; a pegprojecting fromthe faceofisaid pmfiled.- 1plat'e: in the neighbourhood of: they enterlngi end- Ofrthfl profilev thereof, and a screw-clamp formed-with anotchengaged by said peg to enable; the tubing to be bent'to be held against theprofile of said profilediplate-xat the entering end: thereof:

FREDERICK CECIL. DRAPER. 

